In recent years, electric vehicles such as electric automobiles, hybrid vehicles, and fuel cell automobiles which are environmentally friendly have attracted much attention. From the viewpoint of being environmentally friendly, it is desirable to improve energy efficiency, such as improvement of fuel consumption. However, improved fuel consumption may come at the sacrifice of vehicle maneuverability, cabin comfort, etc., in such forms as a limitation of power performance of the vehicle and a limitation on air-conditioning. Therefore, it is desirable to select the energy efficient configuration by a simple operation of a driver. For this purpose, a switch or the like for instructing low-fuel-consumption travel is provided in a controlling unit of the vehicle. Such a switch is often called, for example, an “ecology-mode switch” or an “ecology switch.”
For example, JP Hei 10-248106 A discloses a control device of an electric automobile wherein a mode of a running motor is switched between a normal mode and an ecology mode by operation of a mode selection switch, a high power of 100% is achieved in the normal mode and a low power of 60% is achieved in the ecology mode, and during travel at low power the output is gradually increased to 90% on an uphill road or the like in which the power is insufficient.
In this manner, it is possible to provide a switch to issue the low-fuel-consumption travel instruction and achieve travel with reduced fuel consumption by selection of the driver. In the example of JP Hei 10-248106 A, in the ecology mode, the power is set to the low power of 60% and the output limitation is imposed in order to reduce fuel consumption. An electric vehicle is provided with, for example, a battery, a driving circuit such as a voltage boosting circuit and an inverter circuit, and a dynamo-electric machine for driving and regeneration or the like. Even when the power limitation is imposed, the fuel consumption may fail to be improved if losses in these structures are increased.
An object of the present invention is to provide a control device of an electric vehicle which allows execution of control which improves fuel consumption upon issuance of a low-fuel-consumption travel instruction.